I use the Papago, quite good, bought 2 years ago and got free map update at their office at Ubi 3 months ago.
Last Dec went to Kukup. Coming back around 6.30pm the GPS asked me to enter one small road. Once i turn in, i saw only oil palm plantation, few guys sitting on road side 100 metres away, i immediately 3-point-turn back and go on the main road again towards Pontian. I guess that quiet plantation road is a short-cut, u will come out from Gelang Patah, long ago i travelled before in the morning. By the way, i think GPS usually direct u to the shortest route. So when travelling at night, be careful.
KL, once coming back, gone into an area with many tall buildings, the GPS keeps recalculating itself. Have to rely on signboards to come back, I think i follow the Seremban and Johor signboards.